1. Field of the Invention
The present invention relates to a semiconductor integrated circuit that mounts flip-flop circuits thereon.
2. Description of the Related Art
Various digital equipment, such as digital television sets or digital audio players, has been in widespread use and the demand for LSIs (Large Scale Integration) used for digital signal processing has been ever increasing. A great number of flip-flop circuits are mounted on such LSIs, as fundamental components for sequential circuits.
While energy conservation is being promoted, the reduction in power consumption of LSIs has been long called for. From the viewpoint of extending battery life, the reduction in power consumption is also required for LSIs mounted on battery-powered equipment represented by mobile equipment.
In order to reduce the power consumed by LSIs, various methods, such as reducing a gate size of transistors, have been proposed. However, when such methods are applied to the flip-flop circuits, there are cases where a clock signal or data signal inputted to the flip-flop circuit becomes unsharp or noise like glitch occurs. Such phenomena may cause malfunctions in the flip-flop circuits.
As described above, the power consumption of LSIs and the stability of circuit operation is in a trade-off relation. This is because the circuit operation becomes unstable in trying to reduce the power consumption, whereas it is more difficult to reduce the power consumption as the reliability of circuit operation is raised.